Arteries rings

Kassell (Takahashi et al., 1993) has described the activity of a novel tropolone U88999E in a rabbit model of cerebral vasosjrasm. U88999E inhibits lipid peroxidation and acts as a calcium antagonist. Kassell showed that the compound relaxed preconstricted arterial rings in vitro (potency slightly less than flunarizine or dil-tiazem) and that it reduced vasospasm of basilar arteries after rabbit subarachnoid haemorrhage (Takahashi etal., 1993). 

Archer, S. L., Hampl, V. N. G., Monomethyl-L-arginine causes nitric oxide synthesis in isolated arterial rings trouble in paradise, Biochem. Biophys. Res. Commun. 188 (1992), p. 590-596... 

Hsiao, S. H., Constable, P. D., Smith, G. W., and Haschek, W. M. (2005). Effects of exogenous sphinganine, sphingosine, and sphingosine-l-phosphate on relaxation and contraction of porcine thoracic aortic and pulmonary arterial rings. Toxicol. Sci. 86(1), 194—199. 

Caldum channel antagonist activity was determined in isolated rabbit ear artery rings depolarized by a high K+ concentration [7]. The duration of action in vitro (Dw) was determined by means of wash-out experiments. Rabbit ear artery rings were contracted by a submaximal concentration of calcium, and incubated with the tested compounds for 60 min. Subsequently, they were washed with saline solution until the initial contraction was restored. Dw was defined as the time required by the tissue to recover the basal effect elicited by a submaximal concentration of calcium [8], Antihypertensive activity and Dw were determined in chronically implanted spontaneously hypertensive rats (SHR) [9]. 

Mesenteric artery was studied in the B and D KOs (Table 3). The B KO had no change in PE EC50 or maximum in rings, whereas the D KO had a decreased pressor response to PE in an isolated mesenteric bed preparation (3,7). This evidence for the D in mesenteric arteries fits binding data in WT mice (22a). Carotid and tail artery rings from the B KO had no change in PE effects, except that the carotid from the B KO was more sensitive to PE (7). Coronary arteries were studied in the D and AB KOs by examining coronary flow or pressure in the isolated perfused heart (16,18). Both studies pointed to a role of the D in coronary... 

The vasodilator effects of aromoline, berbamine, isotetrandrine, and (+/-)-N-methylcoclaurine was evaluated in isolated vessels from male Wistar rats. The rats were anesthetized with thiopental (i.p.), and the thoracic aorta was rapidly excised, with the fat with connective tissues being removed. Rings (about 2 mm in length) were cut from the vessel, and fixed in a bath solution. Prior to addition of the alkaloid sample, the arterial rings were... 

The inhibitory influence of NO on eNOS, albeit indirectly, was also observed in vascular endothelial cells, arterial rings, and in vivo in the perfused rabbit hindquarters vascular bed. Excess NO in the form of NO donor compounds inhibited the endothelium-dependent formation of EDRF/... 

In our initial studies we used inhaled nitric oxide as a probe to test the effect of cardiopulmonary bypass on pulmonary endothelial function. Cardiopulmonary bypass may result in damage to the pulmonary endothelium, and the degree of pulmonary hypertension is correlated with the extent of such damage. Acetylcholine-induced vasodilation is attenuated in a number of vascular diseases that impair endothelial function,and preconstricted pulmonary artery rings from explanted lungs of patients with... 

Isolated pig coronary arteries with intact endothelium generated Oj " at a rate of 9.0 0.8 pM per min and mg dry weight (Brandes et al. 1997) this rate was diminished by about 24% when the endothelium was removed. The nitroblue tetrazo-lium staining of arterial ring preparations showed formazan precipitation mainly in the intima. 

Glycogen breakdown induced by concentration above 0.2 mM H2O2 and ferf-butylhydroperoxide is due to a five fold increase in the ratio active glycogen phosphorylase a to inactive phosphorylase b (Heinle 1982, 1989). Concomitantly, ATP is decreased by about 50 % whereas the ATP/ADP ratio is decreased from about 2.3 (as found in fresh arterial tissue) to approximately 1.2. With respect to alterations of contractility, it was found that at concentrations of about 0.3 mM the peroxides were able to induce contraction in relaxed arterial rings (Heinle 1984). This indicates that cytosolic levels of calcium ions are increased under these conditions. Lower peroxide concentrations did not cause contraction. However, even at concentrations of 10 pM, potentiated contraction enhancement was found when the contractile apparatus was simultaneously activated, e.g., by depolarisation. This finding can be interpreted as a facilitative effect of the hydroperoxides on cytosoUc calcium release. The linolenic acid peroxide as synthesised in the reaction with soy bean lipoxidase revealed similar effects on contractility in concentrations up to 20 pM. 

In rabbit artery rings denuded of the endothe-hum and cultured with 0.3 p,M doxorubicin for 7 days, the contractions induced by noradrenaline, but not those induced by endothelin-1 or high lU, were strongly inhibited (Murata et al. 2001). This reaction was followed by a decrease in the induction of the ttiA-adrenoceptor without any change in the mRNA level. Inhibition of noradrenaline-induced contractions by doxorubicin was attenuated by superoxide dismutase (EC 1.15.1.1), and a,A-adrenoceptor protein expression recovered. 

Flow probes Doppler Electromagnetic Ultrasonic Isolated tissue preparations Arterial (rings, spiral strips, perfused) Veins (intacl/denuded endothelium)... 

SM and polysaccharide sulphate (PSS) inhibit the adhesion of erythrocytes, from patients with ceidrral thrombosis, to cultured human umbilical vein endothelial cells (HUVEC) (25). Treatment of SM, PSS, dextran 40 and mannitol improve the viscoelasticity properties of red blood cell suspension (31). SM inhibits the contraction of rai it basilar artery rings evoked by CaCh... 

Antiedema, anti-inflammatory, diuretic, gonadotropic activity, estrogenic activity, and antihypertensive activity were also reported in vivo The antihypertensive activity may be explained in view of a recent report by Kwan et al. in which Siberian ginseng aqueous extract resulted in a concentration-dependent relaxation in different contracted vascular preparations (dog carotid arterial rings, rat aorta, and rat artery) at 0.04—2.0 mg/mL. The observed relaxation was attributed to NO and/ or EDHF, in addition to other possible mechanisms. ... 

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